package net.jpountz.lz4; /* * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.nio.ByteBuffer; import java.util.Arrays; /** * LZ4 compressor. *

* Instances of this class are thread-safe. */ public abstract class LZ4Compressor { /** Return the maximum compressed length for an input of size length. */ @SuppressWarnings("static-method") public final int maxCompressedLength(int length) { return LZ4Utils.maxCompressedLength(length); } /** * Compress src[srcOff:srcOff+srcLen] into * dest[destOff:destOff+destLen] and return the compressed * length. * * This method will throw a {@link LZ4Exception} if this compressor is unable * to compress the input into less than maxDestLen bytes. To * prevent this exception to be thrown, you should make sure that * maxDestLen >= maxCompressedLength(srcLen). * * @throws LZ4Exception if maxDestLen is too small * @return the compressed size */ public abstract int compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff, int maxDestLen); /** * Compress src[srcOff:srcOff+srcLen] into * dest[destOff:destOff+destLen] and return the compressed * length. * * This method will throw a {@link LZ4Exception} if this compressor is unable * to compress the input into less than maxDestLen bytes. To * prevent this exception to be thrown, you should make sure that * maxDestLen >= maxCompressedLength(srcLen). * * {@link ByteBuffer} positions remain unchanged. * * @throws LZ4Exception if maxDestLen is too small * @return the compressed size */ public abstract int compress(ByteBuffer src, int srcOff, int srcLen, ByteBuffer dest, int destOff, int maxDestLen); /** * Convenience method, equivalent to calling * {@link #compress(byte[], int, int, byte[], int, int) compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff)}. */ public final int compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff) { return compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff); } /** * Convenience method, equivalent to calling * {@link #compress(byte[], int, int, byte[], int) compress(src, 0, src.length, dest, 0)}. */ public final int compress(byte[] src, byte[] dest) { return compress(src, 0, src.length, dest, 0); } /** * Convenience method which returns src[srcOff:srcOff+srcLen] * compressed. *

Warning: this method has an * important overhead due to the fact that it needs to allocate a buffer to * compress into, and then needs to resize this buffer to the actual * compressed length.

*

Here is how this method is implemented:

*
   * final int maxCompressedLength = maxCompressedLength(srcLen);
   * final byte[] compressed = new byte[maxCompressedLength];
   * final int compressedLength = compress(src, srcOff, srcLen, compressed, 0);
   * return Arrays.copyOf(compressed, compressedLength);
   * 
*/ public final byte[] compress(byte[] src, int srcOff, int srcLen) { final int maxCompressedLength = maxCompressedLength(srcLen); final byte[] compressed = new byte[maxCompressedLength]; final int compressedLength = compress(src, srcOff, srcLen, compressed, 0); return Arrays.copyOf(compressed, compressedLength); } /** * Convenience method, equivalent to calling * {@link #compress(byte[], int, int) compress(src, 0, src.length)}. */ public final byte[] compress(byte[] src) { return compress(src, 0, src.length); } /** * Compress src into dest. Calling this method * will update the positions of both {@link ByteBuffer}s. */ public final void compress(ByteBuffer src, ByteBuffer dest) { final int cpLen = compress(src, src.position(), src.remaining(), dest, dest.position(), dest.remaining()); src.position(src.limit()); dest.position(dest.position() + cpLen); } @Override public String toString() { return getClass().getSimpleName(); } }